Wireless transmission device, control circuit, and storage medium

Abstract

A wireless transmission device (1) is characterized by being provided with a sounding slot generation unit (10) that generates a transmission signal for reception quality measurement composed of a signal section for each time window length of a fast Fourier transform process executed on a reception side and in which a signal is present, and a non-signal section for interference measurement for each time window length and in which no signal is present. The transmission signal is a burst-shaped low-density pulse signal in which the signal section includes a first region which is a time region in which a pulse signal is present, and a second region in which no pulse signal is present, and the transmission signal is such that the spectrum derived by processing the low-density pulse signal of the signal section including the first region and the second region in a time window length by a fast Fourier transform has a spectrum flatness in a frequency resolution corresponding to the time window length.

Description

Radio transmitting device, control circuit and storage medium

[0001] The present disclosure relates to a wireless transmission device that generates a transmission signal for measuring reception quality, a control circuit, and a storage medium.

[0002] In wireless communications, it is important to accurately grasp the reception conditions of the channels used by the system in order to reduce the effects of wireless signal interference. In systems where interference from other systems exists or systems where reception conditions change frequently, such as mobile communications, it is important to measure reception quality with high accuracy in a short time so that the measured reception quality results can be reflected in communication parameters. For example, in unlicensed bands such as the ISM (Industry-Science-Medical) band, frequencies are shared by multiple communication devices and different communication systems in order to make effective use of radio frequencies, which makes interference more likely to occur and the reception conditions more likely to change frequently.

[0003] A common method for measuring the reception status of a desired signal is to transmit a known signal called a pilot signal between the transmitter and receiver and measure the reception status of the pilot signal at the receiver. Another common method for measuring the reception status of an interfering signal is to provide an interference measurement period during communication where there is no signal for a certain period of time and measure the reception status of the interfering signal.

[0004] When measuring the reception status of both the desired signal and the interference signal, it is possible to divide the time into a desired signal measurement period and an interference measurement period, measuring the reception status of the desired signal in the desired signal measurement period and the reception status of the interference signal in the interference measurement period. In this case, to prevent delayed waves of the desired signal from being mixed into the interference measurement period and reducing the measurement accuracy of the reception status of the interference signal, a method of providing a guard time between the desired signal measurement period and the interference signal measurement period has been considered. However, because the guard time becomes a redundant no-signal period, it is desirable to make it as short as possible in order to achieve reception quality measurement in a short time.

[0005] For example, Patent Document 1 discloses a method for generating a chirp signal with time burst characteristics by signal processing using a digital circuit. By using such a signal with time burst characteristics, it becomes possible to provide a guard time within the desired signal measurement section, and it becomes possible to measure reception quality in a short time.

[0006] JP 2007-64830 A

[0007] However, while the above-described conventional technology enables high-speed processing, it has the problem of potentially reducing the accuracy of measuring the reception status of the desired signal. When measuring the reception status of the desired signal for a signal-carrying section of the above-described burst signal on the receiving side, the measurement section of the desired signal includes delayed waves in order to measure the effects of the communication path between the transmitter and receiver. Therefore, it is preferable that the time window length of the fast Fourier transform used in spectral analysis of the desired signal be a time window length that includes the desired signal and the guard time. However, if fast Fourier transform processing is performed on the above-described burst signal using a time window length that includes the desired signal and the guard time, spectral flatness is lost, resulting in a significant reduction in the accuracy of measuring the reception status of the desired signal.

[0008] The present disclosure has been made in consideration of the above, and aims to provide a wireless transmission device that generates a transmission signal that can measure the reception status of a desired signal and an interference signal with high accuracy in a short period of time.

[0009] In order to solve the above-mentioned problems and achieve the object, a wireless transmission device according to the present disclosure is characterized in that it comprises a sounding slot generation unit that generates a transmission signal for measuring reception quality, which is composed of signal-present intervals in which a signal is present, which are intervals each having a time window length for fast Fourier transform processing executed on the receiving side, and no-signal intervals for interference measurement in which a signal is not present, which are intervals each having a time window length, wherein the signal-present intervals are burst-like low-density pulse-type signals including a first region which is a time domain in which a pulse signal is present and a second region in which no pulse signal is present, and which generates a transmission signal such that the spectrum obtained by fast Fourier transform processing of the low-density pulse-type signal in the signal-present interval including the first region and the second region at the time window length has spectral flatness at a frequency resolution corresponding to the time window length.

[0010] The present disclosure provides an advantage of being able to provide a wireless transmission device that generates a transmission signal that can measure the reception status of a desired signal and an interference signal with high accuracy in a short time.

[0011] FIG. 1 is a diagram showing an example of a functional configuration of a wireless transmission apparatus according to a first embodiment. FIG. 2 is a diagram showing an example of a functional configuration of a sounding slot generation unit according to the first embodiment. FIG. 3 is a diagram showing an example of a sounding slot generated by the sounding slot generation unit. FIG. 4 is a diagram showing an example of a functional configuration of a low-density pulse generation unit according to the first embodiment. FIG. 5 is a diagram showing an example of a waveform of a ZC sequence generated by the ZC sequence generation unit. FIG. 6 is a diagram showing an example of a waveform of an interpolated sequence generated by the sequence interpolation unit. FIG. 7 is a diagram showing an example of a spectral waveform after mapping by the subcarrier mapping unit. FIG. 8 is a diagram showing a spectral waveform after filtering by the frequency filter unit. FIG. 9 is a diagram showing a time waveform after IFFT processing by the IFFT unit. FIG. 10 is a diagram showing a time waveform after time window processing by the time window filter unit. FIG. 11 is a diagram showing a spectrum obtained by FFT-processing a low-density pulse-type signal generated by the low-density pulse generation unit.

[0012] Hereinafter, a wireless transmission device, a control circuit, and a storage medium according to embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments.

[0013] First Embodiment. FIG. 1 illustrates an example of a functional configuration of a wireless transmission device 1 according to a first embodiment. The wireless transmission device 1 includes a sounding slot generation unit 10, a DUC (Digital Up-Converter) 11, an RF (Radio Frequency) unit 12, a wireless antenna 13, and a control unit 14. The wireless transmission device 1 has a function of transmitting a wireless signal to a receiving device (not shown). The sounding slot generation unit 10 generates a digital signal called a sounding slot, which is a transmission slot for measuring reception quality, under the control of the control unit 14, and outputs the generated sounding slot to the DUC 11. The DUC 11 up-converts the sounding slot of the digital signal output by the sounding slot generation unit 10 into an analog signal. The DUC 11 outputs the converted analog signal to the wireless antenna 13. The wireless antenna 13 radiates the analog signal output by the RF 12 into the air. The control unit 14 controls the operation of the wireless transmission device 1. Specifically, the control unit 14 outputs to the sounding slot generating unit 10 an instruction to generate a sounding slot, the configuration of the sounding slot to be generated, and parameter information indicating the values ​​of parameters such as the FFT time window length and sequence length.

[0014] 2 is a diagram illustrating an example of a functional configuration of the sounding slot generation unit 10 according to the first embodiment. The sounding slot generation unit 10 includes a sounding slot generation control unit 100, a low-density pulse generation unit 101, a no-signal interval generation unit 102, and a signal selection unit 103.

[0015] FIG. 3 is a diagram illustrating an example of a sounding slot generated by the sounding slot generation unit 10. The sounding slot generation unit 10 generates a sounding slot, as shown in FIG. 3, which is an interval for each FFT (Fast Fourier Transform) time window length and is composed of a signal interval where a signal is present and a no-signal interval where no signal is present. A low-density pulse is present in the signal interval. Note that the sounding slot configuration illustrated in FIG. 3 is an example, and the sounding slot is composed of a combination of signal intervals and no-signal intervals of any time length. Note that the time window length may be a value predetermined in the wireless communication system, or may be a variable value determined by the wireless transmission device 1 each time a signal interval is generated. If the time window length is variable, the wireless transmission device 1 notifies the wireless reception device (not shown) on the receiving side of the time window length. Furthermore, considering ensuring communication quality, it is desirable that the frequency resolution in the spectrum analysis for reception quality measurement be equal to or greater than that of the signal during communication. For this reason, it is desirable that the time window length used when measuring communication quality be equal to or greater than the time window length during communication.

[0016] The low-density pulse generation unit 101 generates a digital signal for a signal interval in which a low-density pulse is present, as shown in FIG. 3 . The no-signal interval generation unit 102 generates a digital signal for a no-signal interval in which the amplitude is zero, as shown in FIG. 3 . The signal selection unit 103 selects a signal to output from the digital signal for a signal interval output by the low-density pulse generation unit 101 and the digital signal for a no-signal interval output by the no-signal interval generation unit 102, and outputs the selected signal to the downstream block, DUC 11. The sounding slot generation control unit 100 controls the low-density pulse generation unit 101, the no-signal interval generation unit 102, and the signal selection unit 103 to generate a sounding slot. The sounding slot generation control unit 100 controls the low-density pulse generation unit 101, the no-signal interval generation unit 102, and the signal selection unit 103 so that a sounding slot based on the sounding slot configuration instructed by the control unit 14 is generated. When generating a signal interval, sounding slot generation control unit 100 outputs a signal interval generation instruction to low-density pulse generation unit 101, and when generating a no-signal interval, outputs a no-signal interval generation instruction to no-signal interval generation unit 102. When parameters such as FFT time window length and sequence length are changed for each signal interval generation, sounding slot generation control unit 100 also outputs the parameters in accordance with the generation instruction to low-density pulse generation unit 101 and no-signal interval generation unit 102. Sounding slot generation control unit 100 also performs selection control on signal selection unit 103, and controls signal selection unit 103 to select and output an input from low-density pulse generation unit 101 when outputting a signal interval, and to select and output an input from no-signal interval generation unit 102 when outputting a no-signal interval.

[0017] 4 is a diagram illustrating an example of a functional configuration of the low-density pulse generation unit 101 according to the first embodiment. The low-density pulse generation unit 101 includes a ZC (Zadoff-Chu) sequence generation unit 1010, a sequence interpolation unit 1011, a subcarrier mapping unit 1012, a frequency filter unit 1013, an IFFT unit 1014, and a time window filter unit 1015.

[0018] The low-density pulse generating unit 101 generates a low-density pulsed signal in which power is concentrated in an arbitrary time interval within the FFT time window length and the frequency spectrum ensures flatness at the frequency resolution corresponding to the FFT time window length, in accordance with the control of the sounding slot generation control unit 100. The method for generating a low-density pulsed signal by the low-density pulse generating unit 101 will be described below.

[0019] ZC sequence generation section 1010 generates a low-order ZC sequence with a period shorter than the FFT time window length of IFFT section 1014, i.e., the number of IFFT points, and with a gradual phase change. The ZC sequence is generated using, for example, the following equation (1). ZC sequence generation section 1010 outputs the generated ZC sequence to sequence interpolation section 1011.

[0020]

[0021] In equation (1), i is the sequence number, N is the sequence length, and u is the order of the ZC sequence. Here, if the FFT time window length processed by IFFT section 1014 is L, then the sequence length N satisfies N<L. Furthermore, in the generated low-density pulse signal, the signal length of the signal-present region within the FFT time window length is determined by the sequence length N, which is set to an arbitrary length. It is desirable that the order u be as low as possible to make the phase change gradual, and can be set to u=1, for example.

[0022] Fig. 5 is a diagram showing an example of the waveform of a ZC sequence generated by ZC sequence generating section 1010. Fig. 5 shows the waveform of a ZC sequence generated using equation (1).

[0023] Returning to the explanation of Figure 4, sequence interpolation section 1011 performs interpolation processing on the ZC sequence output by ZC sequence generation section 1010. The interpolation processing performed by sequence interpolation section 1011 is low-amplitude phase interpolation processing. Sequence interpolation section 1011 outputs an interpolated sequence, which is the sequence after the interpolation processing, to subcarrier mapping section 1012. Sequence interpolation section 1011 performs interpolation processing so that there is a minimum phase transition and a constant envelope between signal points. Furthermore, sequence interpolation section 1011 interpolates so that the number of sequences after interpolation is the number of IFFT points, L. Therefore, the number of interpolation points is "L / N".

[0024] Fig. 6 is a diagram showing an example of the waveform of an interpolated sequence generated by sequence interpolation section 1011. Fig. 6 shows the waveform of an interpolated sequence obtained by interpolating the ZC sequence of Fig. 5 so that there is a minimum phase transition and a constant envelope between signal points. It can be seen from Fig. 6 that the amount of phase change in the region of Fig. 5 where there is a large phase change has been made gentler by the interpolation process.

[0025] Returning to the explanation of Figure 4, the subcarrier mapping unit 1012 maps the interpolated sequence output by the sequence interpolation unit 1011 to each subcarrier. The subcarrier mapping unit 1012 outputs the signal mapped to the subcarriers to the frequency filter unit 1013. Taking into account the frequency filter processing at the subsequent stage, the subcarrier mapping unit 1012 arranges the generated interpolated sequence so that its phase change region is at the band edge. Here, the phase change region refers to a region within a sequence where the amount of phase change between sequences is large.

[0026] Fig. 7 is a diagram showing an example of a spectral waveform after mapping by subcarrier mapping section 1012. Fig. 7 shows a spectral waveform in which the interpolated sequence shown in Fig. 6 is mapped to each subcarrier. It can be seen that areas with large phase change amounts are located at both ends of the band, and an area with small phase change amounts is located in the center of the band.

[0027] Returning to the explanation of Fig. 4 , the frequency filter unit 1013 secures a guard band at the band edge by filtering to prevent out-of-band radiation of the generated low-density pulse-type signal. The filter used in the frequency filter unit 1013 is not particularly limited and may be a general filter. The frequency filter unit 1013 outputs the filtered signal to the IFFT unit 1014.

[0028] Fig. 8 is a diagram showing a spectral waveform after filtering by the frequency filter unit 1013. Fig. 8 shows the spectral waveform of the signal after filtering by the frequency filter unit 1013 for the signal after subcarrier mapping shown in Fig. 7. It can be seen that guard bands are provided at both ends of the band.

[0029] Returning to the description of Fig. 4, the IFFT unit 1014 converts the post-filtering signal output by the frequency filter unit 1013 from a frequency domain signal to a time domain signal. At this time, the IFFT unit 1014 performs processing with L IFFT points, and generates a signal with a time window length L after the IFFT processing. The IFFT unit 1014 outputs the post-IFFT signal to the time window filter unit 1015.

[0030] 9 is a diagram showing a time waveform after IFFT processing by IFFT section 1014. As a result of performing interpolation processing on a low-order ZC sequence, the signal after IFFT processing becomes a burst-like signal within the time window length L, with power concentrated at point N within the time window length L. In the following description, sections within the FFT time window length where power is concentrated will be referred to as signal-present regions, and regions other than signal-present regions will be referred to as gap regions. A low-density pulse signal exists in the signal-present regions, and no low-density pulse signal exists in the gap regions.

[0031] Returning to the description of FIG. 4 , the time window filter unit 1015 performs time window processing on the post-IFFT signal output by the IFFT unit 1014. The time window filter unit 1015 outputs the post-IFFT signal to the signal selection unit 103. The time window filter unit 1015 uses time window processing to remove residual signal components in gap regions. At this time, if the signal-present region of the time signal after IFFT processing is divided as shown in FIG. 9 , the time window filter unit 1015 performs time shift processing so that the signal-present region becomes a single section. Furthermore, the time window filter unit 1015 is required to perform processing so that the amplitude of the signal-present region is not distorted, so that spectral flatness is not impaired by the time window processing. For this reason, the time window filter unit 1015 is realized, for example, by a filter whose value is constant in a specific section, such as a raised cosine filter, and performs filtering so that the signal-present region is processed within the flat section of the filter.

[0032] Fig. 10 is a diagram showing a time waveform after time window processing by the time window filter unit 1015. In Fig. 10, the residual signal components in the gap regions of the signal in Fig. 9 are cut off, and time shift processing is performed so that the signal-containing region becomes a single section.

[0033] The low-density pulse generation unit 101 generates a low-density pulse-type signal in which power is concentrated in an arbitrary section within the FFT time window length through the processing described above, and outputs the generated low-density pulse-type signal. Furthermore, when the low-density pulse-type signal generated by the low-density pulse generation unit 101 is subjected to FFT processing with the FFT time window length L at the time of generation, it becomes a signal having spectrum flatness with a frequency resolution corresponding to the time window length.

[0034] 11 is a diagram showing a spectrum obtained by FFT processing of the low-density pulse type signal generated by the low-density pulse generating unit 101. Fig. 11 shows a spectrum obtained by FFT processing with an FFT time window length L. The signal has spectral flatness at a frequency resolution corresponding to the time window length L.

[0035] FIG. 12 is a diagram illustrating an example of the functional configuration of the no-signal interval generating unit 102 according to the first embodiment. The no-signal interval generating unit 102 is configured with a memory unit 1020. The memory unit 1020 stores signal data for generating no-signal intervals. The no-signal interval generating unit 102 generates no-signal intervals in which there is no signal, i.e., the amplitude is zero, in all intervals of the FFT time window length L'. In the first embodiment, the no-signal interval generating unit 102 generates no-signal intervals of the FFT time window length by reading signal data stored in the memory unit 1020 for the FFT time window length L' or by repeatedly reading the same data L' times. Note that the configuration of the no-signal interval generating unit 102 shown in FIG. 11 is merely an example, and the unit may be implemented as a circuit that generates intervals of any time length in which the amplitude is zero.

[0036] As described above, the wireless transmission device 1 according to the first embodiment is characterized by comprising a sounding slot generation unit 10 that generates a transmission signal for measuring reception quality, which is composed of signal-present intervals in which a signal is present, which are intervals corresponding to the time window length of fast Fourier transform processing executed on the receiving side, and no-signal intervals for interference measurement in which a signal is not present, which are intervals corresponding to the time window length, wherein the signal-present intervals are burst-like low-density pulse-type signals including signal-present areas which are first areas that are time domains in which a pulse signal is present and gap areas which are second areas in which a pulse signal is not present, and which generates a transmission signal such that the spectrum obtained by fast Fourier transform processing, using the time window length, of the low-density pulse-type signal in the signal-present interval including the first area and the second area has spectral flatness at a frequency resolution corresponding to the time window length.

[0037] With the above-described configuration, the wireless transmission device 1 has the effect of being able to measure the reception status of a desired signal and an interference signal with high accuracy in a short time. Specifically, the wireless transmission device 1 can generate a transmission signal for reception quality measurement that has the following three characteristics: (1) The signal in the signal-containing section has spectral flatness at a frequency resolution corresponding to the FFT time window length; (2) A no-signal region is provided in the signal-containing section, which functions as a guard time to prevent delayed waves from being mixed into the interference measurement section; and (3) The signal in the signal-containing section is a burst-like low-density pulse signal that becomes a signal-containing region in any section within the FFT time window length.

[0038] The above feature (1) improves the estimation accuracy when performing FFT transformation on the receiving side to estimate the desired signal. Furthermore, the features (2) and (3) prevent delayed waves of signals in signal-present intervals from being mixed into the interference measurement interval. Furthermore, by providing a no-signal region that serves as a guard time within the signal-present interval, it is no longer necessary to provide a redundant guard time between the signal-present interval for measuring the desired signal and the no-signal interval for measuring interference, enabling the reception status to be measured in a short time.

[0039] 13 is an explanatory diagram of the effect of the wireless transmission device 1. As shown in FIG. 13, with a conventional signal that does not include a gap area, there is a high possibility that a delayed wave of a signal in a desired signal measurement section will be mixed into an interference measurement section. As a result, in the interference measurement section, it is impossible to distinguish whether the signal being measured is a delayed wave or an interference wave, which reduces the accuracy of measuring the reception status. With the transmission signal transmitted by the wireless transmission device 1, as shown in FIGS. 3 and 10, a gap area is provided after the signal-present section within the signal-present section, so that the delayed wave of the signal in the signal-present section will be present in the gap area, preventing delayed waves from being mixed into the no-signal section used for interference measurement.

[0040] The sounding slot generation unit 10 also has a low-density pulse generation unit 101 that generates a low-density pulse-type signal in a signal-present section, and the low-density pulse generation unit 101 performs low-amplitude phase interpolation processing on a signal generated based on a Zadoff-Chu sequence that has a shorter period and lower order than the time window length, and outputs a low-density pulse-type signal that is generated by performing subcarrier mapping processing in which the sequence after the low-amplitude phase interpolation processing is mapped to each subcarrier.

[0041] The low-density pulse generation unit 101 includes a ZC sequence generation unit 1010, which is a sequence generation unit that generates a Zadoff-Chu sequence with a shorter period and lower order than the time window length, a sequence interpolation unit 1011 that performs low-amplitude phase interpolation processing on the Zadoff-Chu sequence generated by the ZC sequence generation unit 1010, and a subcarrier mapping unit 1012 that performs subcarrier mapping processing to map the sequence after the low-amplitude phase interpolation processing to each subcarrier.

[0042] The low-density pulse generator 101 may further include an IFFT unit 1014, which is an inverse fast Fourier transform unit that converts the signal after the subcarrier mapping process into a time-domain signal, and a time window filter unit 1015 that performs time window processing on the converted time-domain signal using a time window filter that has time flatness. By using the time window filter, it is possible to cut off residual signal components in gap regions.

[0043] Furthermore, the sounding slot generating unit 10 of the wireless transmitting device 1 can generate at least one of the low-density pulse type signal in the signal-present section and the signal in the no-signal section by reading out signal data stored in advance in a memory. In the first embodiment, an example has been described in which the signal in the no-signal section is generated by reading out signal data stored in advance in the memory unit 1020.

[0044] Second Embodiment Fig. 14 is a diagram showing an example of the functional configuration of a low-density pulse generation unit 101 according to a second embodiment. The low-density pulse generation unit 101 includes a memory unit 1016. Note that the configuration of the second embodiment is the same as that of the first embodiment except for the low-density pulse generation unit 101. That is, the wireless transmission device 1 includes a sounding slot generation unit 10, a DUC 11, an RF 12, a wireless antenna 13, and a control unit 14. The sounding slot generation unit 10 includes a low-density pulse generation unit 101, a no-signal interval generation unit 102, a signal selection unit 103, and a sounding slot generation control unit 100. The following mainly describes the differences from the first embodiment.

[0045] The memory unit 1016 stores IQ amplitude values ​​of signal-present intervals that are generated in the same procedure as in the low-density pulse generation unit 101 of Embodiment 1, and output values ​​of one signal-present interval in the low-density pulse generation unit 101 of Embodiment 1. The signal-present interval pattern to be stored at this time may be a single pattern or multiple patterns.

[0046] The low-density pulse generating section 101 receives an instruction to generate a signal-containing section and parameter information of the output signal from the sounding slot generation control section 100, and reads out amplitude information of the signal-containing section according to the parameters from the memory section 1016 and outputs it.

[0047] As in the first embodiment, the sounding slot generation control unit 100 controls the low-density pulse generation unit 101, the no-signal interval generation unit 102, and the signal selection unit 103 so that a sounding slot is generated based on the sounding slot configuration instructed by the control unit 14. When generating a signal interval, the sounding slot generation control unit 100 outputs an instruction to generate a signal interval to the low-density pulse generation unit 101, and when generating a no-signal interval, outputs an instruction to generate a no-signal interval to the no-signal interval generation unit 102. When changing parameters such as the FFT time window length and sequence length for each signal interval generation, the sounding slot generation control unit 100 also outputs the parameters to each of the low-density pulse generation unit 101 and the no-signal interval generation unit 102 in accordance with the generation instruction. The sounding slot generation control unit 100 also performs selection control of the signal selection unit 103, controlling it to select and output an input from the low-density pulse generation unit 101 when outputting a signal interval, and to select and output an input from the no-signal interval generation unit 102 when outputting a no-signal interval.

[0048] The DUC 11 up-converts the digital signal generated by the sounding slot generating unit 10 into an analog signal, and outputs the generated analog signal to the RF 12.

[0049] The RF 12 converts the baseband signal, which has been converted into an analog signal, into a carrier frequency, amplifies the signal, and then outputs it to the radio antenna 13 .

[0050] The radio antenna 13 radiates the signal from the RF 12 into the air.

[0051] As in the first embodiment, the control unit 14 outputs to the sounding slot generating unit 10 an instruction to generate a sounding slot, and information on the configuration and parameters of the sounding slot to be generated.

[0052] As described above, sounding slot generation unit 10 of wireless transmission device 1 can generate at least one of a low-density pulse type signal for a signal-present interval and a signal for a no-signal interval by reading signal data stored in advance in memory. In embodiment 2, an example was described in which a low-density pulse type signal for a signal-present interval is generated by reading signal data stored in memory unit 1016 in advance. In wireless transmission device 1 having low-density pulse generation unit 101 configured with memory unit 1016 as described in embodiment 2, no-signal interval generation unit 102 may include memory unit 1020 for storing signal data as shown in FIG. 12 as described in embodiment 1, or may be implemented as a circuit that generates an interval of any time length in which the amplitude is 0. Even with such a configuration, the same effects as those of embodiment 1 can be achieved.

[0053] Third Embodiment Fig. 15 is a diagram showing an example of the functional configuration of a sounding slot generation unit 10 according to a third embodiment. The sounding slot generation unit 10 is composed of a sounding slot memory control unit 104 and a memory unit 105. Note that in the third embodiment, the configuration other than the sounding slot generation unit 10 is the same as in the first embodiment. That is, the radio transmitting device 1 has a sounding slot generation unit 10, a DUC 11, an RF 12, a radio antenna 13, and a control unit 14. The DUC 11, RF 12, radio antenna 13, and control unit 14 are the same as in the first embodiment.

[0054] Sounding slot memory control section 104 outputs to memory section 105 an output instruction and pattern information of the sounding slot to be output, based on the instruction to generate the sounding slot and parameter information of the sounding slot input from control section 14 .

[0055] The memory unit 105 stores the IQ amplitude values ​​of the sounding slots. At this time, the sounding slot patterns stored may be a single one or multiple ones. The memory unit 105 outputs the sounding slots corresponding to the output instructions and pattern information output by the sounding slot memory control unit 104.

[0056] The DUC 11 up-converts the digital signal generated by the sounding slot generating unit 10 into an analog signal, and outputs the generated analog signal to the RF 12.

[0057] The RF 12 converts the baseband signal, which has been converted into an analog signal, into a carrier frequency, amplifies the signal, and then outputs it to the radio antenna 13 .

[0058] The radio antenna 13 radiates the signal from the RF 12 into the air.

[0059] As in the first embodiment, the control unit 14 outputs to the sounding slot generating unit 10 an instruction to generate a sounding slot, and information on the configuration and parameters of the sounding slot to be generated.

[0060] As described above, the sounding slot generating unit 10 of the wireless transmitting device 1 can generate at least one of a low-density pulse type signal in a signal section and a signal in a no-signal section by reading out signal data stored in advance in memory. In the third embodiment, an example was described in which both a burst-like low-density pulse type signal in a signal section and a signal in a no-signal section are generated by reading out signal data stored in advance in memory unit 105. With this configuration, it is possible to achieve the same effects as in the first embodiment.

[0061] Fourth Embodiment. FIG. 16 is a diagram illustrating an example of a functional configuration of a wireless transmission device 1 according to a fourth embodiment. The wireless transmission device 1 includes sounding slot generation units 10-1 and 10-2, DUCs 11-1 and 11-2, RFs 12-1 and 12-2, wireless antennas 13-1 and 13-2, and a control unit 14. The wireless transmission device 1 includes a plurality of components other than the control unit 14, one for each system corresponding to the wireless antennas 13-1 and 13-2. Here, the wireless transmission device 1 includes two systems corresponding to the two wireless antennas 13-1 and 13-2, respectively, and these systems are referred to as branch #1 and branch #2. Multiple components having similar functions are distinguished from one another by adding a hyphen and another number after the common number. The number following the hyphen indicates the system to which the component belongs. That is, of the multiple sounding slot generators 10, the one belonging to system #1 will be referred to as sounding slot generator 10-1, and the one belonging to system #2 will be referred to as sounding slot generator 10-2. Also, in the following description, when there is no need to distinguish between multiple components having similar functions, only common reference numerals may be used. For example, when there is no need to distinguish between sounding slot generators 10-1 and 10-2, they will simply be referred to as sounding slot generator 10.

[0062] The sounding slot generation units 10-1 and 10-2 output sounding slots corresponding to the sounding slot generation instructions, sounding slot configurations, and parameter information input from the control unit 14. The configuration of each sounding slot generation unit 10 is the same as that described in any of the first to third embodiments. Note that the sounding slot configurations output from each sounding slot generation unit 10 may be different for each branch, or may be the same. The sounding slot generation unit 10-1 outputs the generated digital signal of the sounding slot to the DUC 11-1. The sounding slot generation unit 10-2 outputs the generated digital signal of the sounding slot to the DUC 11-2.

[0063] DUCs 11-1 and 11-2 upconvert the digital signals output by the corresponding sounding slot generation units 10 to analog signals. DUC 11-1 upconverts the digital signals output by sounding slot generation unit 10-1 to analog signals and outputs the converted signals to RF 12-1. DUC 11-2 upconverts the digital signals output by sounding slot generation unit 10-2 to analog signals and outputs the converted baseband signals to RF 12-2.

[0064] RF12-1 and 12-2 convert the baseband signal output by the corresponding DUC 11 to a carrier frequency, amplify the signal, and output it to the corresponding radio antenna 13. RF12-1 converts the baseband signal output by DUC 11-1 to a carrier frequency, amplifies the signal, and output it to the radio antenna 13-1. RF12-2 converts the baseband signal output by DUC 11-2 to a carrier frequency, amplifies the signal, and output it to the radio antenna 13-2.

[0065] The radio antennas 13-1 and 13-2 radiate into the air the signals output by the corresponding RF 12. The radio antenna 13-1 radiates into the air the signals output by the RF 12-1, and the radio antenna 13-2 radiates into the air the signals output by the RF 12-2.

[0066] Although the above description shows a configuration in which there are two radio antennas 13, the number of radio antennas 13 may be two or more. In the case of three or more radio antennas 13, the radio transmitting device 1 is configured to include a sounding slot generating unit 10, a DUC 11, an RF 12, and a radio antenna 13 corresponding to each branch, and the functions of each unit are the same as those described above.

[0067] As described above, in the fourth embodiment, a configuration example of the wireless transmission device 1 including a plurality of wireless antennas 13 has been described. According to the above configuration, the wireless transmission device 1 that transmits a transmission signal using a plurality of wireless antennas 13 can also achieve the same effects as those of the first embodiment.

[0068] Next, a hardware configuration of the wireless transmission device 1 according to the first to fourth embodiments of the present disclosure will be described. The functions of each unit of the wireless transmission device 1 are realized by a processing circuit. These processing circuits may be realized by dedicated hardware or may be control circuits using a CPU (Central Processing Unit).

[0069] When the above processing circuits are realized by dedicated hardware, they are realized by a processing circuit 90 shown in Fig. 17. Fig. 17 is a diagram showing dedicated hardware for realizing the functions of the wireless transmission device 1 according to the first to fourth embodiments. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0070] When the processing circuit is realized by a control circuit using a CPU, the control circuit is, for example, a control circuit 91 having a configuration shown in FIG. 18 . FIG. 18 is a diagram showing the configuration of the control circuit 91 for realizing the functions of the wireless transmission device 1 according to the first to fourth embodiments. As shown in FIG. 18 , the control circuit 91 includes a processor 92 and a memory 93. The processor 92 is a CPU, and is also called a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), etc. The memory 93 is, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable read-only memory (EPROM), an EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, a DVD (Digital Versatile Disk), etc.

[0071] When the above processing circuit is realized by the control circuit 91, it is realized by the processor 92 reading and executing a program corresponding to the processing of each component, which is stored in the memory 93. The memory 93 is also used as a temporary memory for each process executed by the processor 92. The program executed by the processor 92 may be provided in a state stored in a storage medium, or may be provided via a communication path such as the Internet.

[0072] As described above, the techniques of the first to fourth embodiments may be realized as a control circuit 91 for realizing the functions of the wireless transmission device 1. The control circuit 91 controls the wireless transmission device 1 and causes the wireless transmission device 1 to execute the steps of generating a transmission signal for reception quality measurement, the transmission signal being composed of signal-present intervals in which a signal is present, which are intervals corresponding to a time window length of fast Fourier transform processing executed on the receiving side, and no-signal intervals for interference measurement in which a signal is not present, which are intervals corresponding to the time window length, the signal-present intervals being a burst-like low-density pulse-type signal including a first region which is a time domain in which a pulse signal is present and a second region in which no pulse signal is present, and the spectrum obtained by fast Fourier transform processing, using the time window length, of the low-density pulse-type signal in the signal-present interval including the first region and the second region has spectral flatness at a frequency resolution corresponding to the time window length.

[0073] Furthermore, the techniques of the above first to fourth embodiments may be realized as a storage medium storing a program for causing the control circuit 91 to control the wireless transmission device 1. This program causes the wireless transmission device 1 to execute the steps of generating a transmission signal for reception quality measurement, which is made up of signal-present intervals in which a signal is present, which are intervals corresponding to a time window length of fast Fourier transform processing executed on the receiving side, and no-signal intervals for interference measurement in which a signal is not present, which are intervals corresponding to the time window length, wherein the signal-present intervals are burst-like low-density pulse-type signals including a first region which is a time domain in which a pulse signal is present and a second region in which no pulse signal is present, and wherein the spectrum obtained by fast Fourier transform processing, using the time window length, of the low-density pulse-type signal in the signal-present interval including the first region and the second region has spectral flatness at a frequency resolution corresponding to the time window length.

[0074] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, and parts of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0075] 1 Radio transmitting device, 10, 10-1, 10-2 Sounding slot generation unit, 11, 11-1, 11-2 DUC, 12, 12-1, 12-2 RF, 13, 13-1, 13-2 Radio antenna, 14 Control unit, 90 Processing circuit, 91 Control circuit, 92 Processor, 93 Memory, 100 Sounding slot generation control unit, 101 Low density pulse generation unit, 102 No signal interval generation unit, 103 Signal selection unit, 104 Sounding slot memory control unit, 105, 1016, 1020 Memory unit, 1010 ZC sequence generation unit, 1011 Sequence interpolation unit, 1012 Subcarrier mapping unit, 1013 Frequency filter unit, 1014 IFFT unit, 1015 Time window filter unit.

Claims

1. A radio transmitting device comprising: a sounding slot generating unit that generates a transmission signal for measuring reception quality, the transmission signal being composed of signal sections where a signal is present, which are sections for each time window length of fast Fourier transform processing executed on the receiving side, and no-signal sections for interference measurement, which are sections for each time window length and where no signal is present, wherein the signal sections are burst-shaped low-density pulse-type signals including a first region which is a time domain where a pulse signal is present and a second region where the pulse signal is not present, and the transmission signal such that the spectrum obtained by fast Fourier transform processing of the low-density pulse-type signal in the signal sections including the first region and the second region at the time window length has spectral flatness at a frequency resolution corresponding to the time window length.

2. The radio transmitting device according to claim 1, characterized in that the sounding slot generating unit has a low-density pulse generating unit that generates the low-density pulse type signal in the signal-carrying section, and the low-density pulse generating unit performs low-amplitude phase interpolation on a signal generated based on a Zadoff-Chu sequence that has a shorter period and lower order than the time window length, and outputs the low-density pulse type signal that is generated by performing subcarrier mapping processing that maps the sequence after the low-amplitude phase interpolation processing to each subcarrier.

3. The radio transmitting device according to claim 1, characterized in that the sounding slot generating unit has a low-density pulse generating unit that generates the low-density pulse type signal in the signal-carrying section, and the low-density pulse generating unit has: a sequence generating unit that generates a Zadoff-Chu sequence having a shorter period and lower order than the time window length; a sequence interpolating unit that performs low-amplitude phase interpolation processing on the Zadoff-Chu sequence; and a subcarrier mapping unit that performs subcarrier mapping processing to map the sequence after the low-amplitude phase interpolation processing to each subcarrier.

4. The radio transmission device according to claim 3, characterized in that the low-density pulse generation unit further comprises: an inverse fast Fourier transform unit that converts the signal after the subcarrier mapping process into a signal in the time domain; and a time window filter unit that performs time window processing on the converted time domain signal using a time window filter that has time flatness.

5. The radio transmitting device according to claim 1, characterized in that the sounding slot generating unit generates at least one of the low-density pulse type signal in the signal-present section and the signal in the no-signal section by reading out signal data stored in advance in a memory.

6. A control circuit for controlling a wireless transmission device, the control circuit causing the wireless transmission device to perform the following steps: generate a transmission signal for measuring reception quality, the transmission signal being composed of signal-present intervals, which are intervals for each time window length of fast Fourier transform processing executed on the receiving side and in which a signal is present, and no-signal intervals for interference measurement, which are intervals for each time window length and in which no signal is present, wherein the signal-present intervals are burst-shaped low-density pulse-type signals including a first region which is a time domain in which a pulse signal is present and a second region in which the pulse signal is not present; and the transmission signal such that the spectrum obtained by fast Fourier transform processing of the low-density pulse-type signal in the signal-present intervals including the first region and the second region with the time window length has spectral flatness at a frequency resolution corresponding to the time window length.

7. A storage medium storing a program for controlling a wireless transmission device, the storage medium causing the wireless transmission device to execute the following steps: generating a transmission signal for reception quality measurement, the transmission signal being composed of signal sections where a signal exists, which are sections for each time window length of fast Fourier transform processing executed on the receiving side, and no-signal sections for interference measurement, which are sections for each time window length and where no signal exists, wherein the signal sections are burst-shaped low-density pulse-type signals including a first region which is a time domain where a pulse signal exists and a second region where the pulse signal does not exist, and the transmission signal such that the spectrum obtained by fast Fourier transform processing of the low-density pulse-type signal in the signal sections including the first region and the second region with the time window length has spectral flatness at a frequency resolution corresponding to the time window length.